Combination of searches for the Higgs boson using the full CDF data set

Abstract

We present a combination of searches for the standard model Higgs boson using the full CDF run II data set, which corresponds to an integrated luminosity of 9.45–10.0 fb[superscript −1] collected from s√ = 1.96 TeV p[¯ over p] collisions at the Fermilab Tevatron. The searches consider Higgs boson production from gluon-gluon fusion, vector-boson fusion, and associated production with either a W or Z boson or a t[¯ over t] pair. Depending on the production mode, Higgs boson decays to W[superscript +]W[superscript −], ZZ, b[¯ over b], τ[superscript +]τ[superscript −], and γγ are examined. We search for a Higgs boson with masses (m[subscript H]) in the range 90–200 GeV/c[superscript 2]. In the absence of a signal, we expect based on combined search sensitivity to exclude at the 95% credibility level the mass regions 90 < m[subscript H] < 94 GeV/c[superscript 2], 96 < m[subscript H] < 106 GeV/c[superscript 2], and 153 < m[subscript H] < 175 GeV/c[superscript 2]. The observed exclusion regions are 90 < m[subscript H] < 102 GeV/c[superscript 2] and 149 < m[subscript H] < 172 GeV/c[superscript 2]. A moderate excess of signal-like events relative to the background expectation at the level of 2.0 standard deviations is present in the data for the m[subscript H] = 125 GeV/c[superscript 2] search hypothesis. We also present interpretations of the data within the context of a fermiophobic model and an alternative standard model incorporating a fourth generation of fermions. Finally, for the hypothesis of a new particle with mass 125 GeV/c[superscript 2], we constrain the coupling strengths of the new particle to W[superscript ±] bosons, Z bosons, and fermions.